The invention relates to electric motors, in particular electronically commutated electric motors, such as a claw-pole motor, for example.
Electric motors, in particular claw-pole motors, are known from the prior art. Claw-pole motors are used whenever low rotation speeds are required. For example, claw-pole motors are used for water pumps or the like.
Claw-pole motors have two (wound) stator coils running in a circumferential direction which surround a claw arrangement. The claw arrangement represents the stator of the electric motor and comprises stator teeth aligned in the axial direction, with which an alternating magnetic field can be produced. The claw arrangement is generally formed in two parts with subarrangements of magnetic material, with each of the subarrangements having a ring from which stator teeth protrude in the axial direction (i.e. perpendicular to the ring face). Furthermore, each of the subarrangements has on one side, at one end of the stator teeth, a section extending radially outwards.
The subarrangements are designed to be complementary with respect to one another, the outer ends, in a radial direction, of the subarrangements being connected to one another in the assembled state via a ring-shaped lamination in such a way that a magnetic return path is formed between the subarrangements. The claw arrangement forms a toroidal stator, with the stator coils being arranged in the interior of the torus. The claws of the subarrangements engage in one another in the assembled state in such a way that they do not touch one another and have equal distances with respect to one another. Depending on the energization of the stator coils, adjacent claws form a south pole and a north pole, or vice versa.
In general, an armature in the form of a rotor which is generally formed with permanent magnets or from a ferrite material is located in the region surrounded by the claw arrangement of the claw-pole motor. By alternately energizing the stator coils, the polarity of adjacent stator teeth is changed, as a result of which a force is exerted on the rotor and the rotor is driven.
Supplying such an electric motor with an alternating electrical variable results in electromagnetic interference (EMI). Such interference, in particular the emission of electromagnetic radiation by conductors and conducted interference can be brought about by electrical components in the electric motor and by metal component parts which are excited to produce EMI emission as a result of magnetic eddy currents. In general, the emission is reduced by further electrical component parts, such as capacitors and inductor coils, for example, being integrated in the drive circuit or in the electric motor. However, this is involved and increases the susceptibility of the entire system to faults.
Therefore, the object of the present invention is to provide an electronically commutated electric motor in which the EMI emission is reduced.